Energy is one of the most interesting and controversial subjects in the history of the world. Human beings have always been in constant search and struggle to find and exploit various sources of energy. Coal and crude oil are two of the most accessible yet complicated sources of energy especially with the environmental and economic issues facing us. Production and use of coal and its derivatives demand cleaner and more efficient ways, while aggregation and deposition of petroleum asphaltenes in the oil reservoirs and processing facilities cause enormous economic loss to the oil industry. This book describes a structural and interfacial study of petroleum asphaltenes and coal tar pitch (a coal derivative), leading to the better understanding of molecular characteristics of fossil fuel hydrocarbons. Analytical techniques such as Size Exclusion Chromatography, Matrix Assisted Laser Desorption/Ionisation- Time of Flight- Mass Spectrometry, Fourier Transform Infrared Spectroscopy, and Atomic Force Microscopy were exploited to provide a comprehensive insight to the molecular structures, mass distributions and interfacial characteristics of coal tar pitch and petroleum asphaltenes.